The present invention relates to an exhaust gas installation with muffler or silencer for a turbocharged reciprocating piston internal combustion engine in which the exhaust gas line consists of a main line leading to the turbine of the turbocharger and of a bypass line bypassing the turbine and controlled by a bypass valve.
In an exhaust gas installation as is schematically illustrated in the patent application No. P 37 15 061.8, the exhaust gases of the main line and of the bypass line are combined in a silencer or muffler before they reach the atmosphere. If an internal combustion engine equipped with such an exhaust gas installation is to operate optimally as aircraft engine at different geodetic heights, then the intensity of the bypass flow to the main flow must have in each case a corresponding ratio. The location in the muffler or silencer where the exhaust gas flows from the main line and from the bypass line mix, must be so constructed that a low-loss mixing can take place which is as noiseless as possible.
It is the object of the present invention to improve the overall efficiency of the internal combustion engine and to dampen effectively the exhaust gas noises by a particular construction of the exhaust gas system and especially of the muffler or silencer installed into the same.
The underlying problems are solved according to the present invention in that the main line and the bypass line terminate in the housing of the muffler or silencer so aligned to one another that the exhaust gas flow of the main line exerts an ejector effect on the exhaust gas flow of the bypass line. If the exhaust gas of the by pass line is admixed to the exhaust gas flow in the main line by ejector action, the mixing takes place in the turbulent edge area of the free jet produced by the main flow. The turbulences and flow losses can be kept small in this manner. The overall efficiency of the internal combustion engine is increased. At the same time, an effective damping of the exhaust gas noises is attained by the ejector-admixing in the muffler or silencer. For that purpose, the main line is connected to a central pipe or tubular member secured in the housing of the muffler or silencer, from which the exhaust gas exits as free jet. The bypass flow is blown into an opening surrounding this free jet. Additionally, the suction of the free jet acts on the by-pass flow and effects its mixing with the turbulent edge air zone of the free jet without the occurrence of larger flow losses.
For purposes of regaining pressure and therewith for increasing the efficiency of the turbine, the central pipe is widened diffusor-like in the flow direction; the lead angle amounts to about 4.degree.. For purposes of noise reduction the bypass flow is introduced strongly throttled into an annular space of the silencer or muffler housing surrounding the central pipe and reaches from there the opening.
The noise of the main and bypass flow is dampened in common in a nozzle pipe coaxial to the central pipe which is provided with a large number of radial bores and is surrounded with a packing of damping-wool.